Synthesis and luminescence properties of copper iodide cluster scintillators incorporating 15-crown-5–alkali metal complexes

CuI cluster scintillators incorporating 15-crown-5 (CH 2 CH 2 O) 5 –alkali metal complexes: (15-crown-5) 2 Cs 2 Cu 2 I 4 (15CCI-1), (15-crown-5) 4 Cs 2 Cu 2 I 4 (15CCI-2), (15-crown-5) 8 Rb 4 Cu 9 I 13 (15RCI), (15-crown-5) 8 K 4 Cu 9 I 13 (15KCI), and (15-crown-5) 6 Na 4 (H 2 O) 3.5 Cu 8 I 12 (15NCI) were synthesized using the solution method. 15CCI-1 and 15CCI-2 samples contained isolated [Cu 2 I 4 ] 2- cluster units, whereas 15RCI and 15KCI formed [Cu 9 I 13 ] 4- cluster structures composed of [Cu 4 I 6 ] 2- and [Cu 5 I 7 ] 2- units, and 15NCI contained isolated [Cu 4 I 6 ] 2- cluster units. In photoluminescence, 15CCI-1 showed broad emission peaks at 400–700 nm, 15CCI-2 exhibited longer-wavelength peaks at 600–800 nm, and the other samples showed broad yellow emission peaks at 500–700 nm. Among the samples, 15CCI-1 showed the best scintillation performance, with the highest light yield value of 32,000 photons/MeV, which was approximately twice that of CdWO 4 crystal measured under the same conditions.